Myoelectric activity of the stomach : gastroelectromyography and electrogastrography

The musculature of the distal two-thirds of the stomach generates electrical signals that are related, in a complex manner, to the (peristaltic) contractions of these muscles. These electrical signals originate in ion shifts from the intracellular to the extracellular space and vice-versa. Apart from recording intracellular electrical activity with the aid of a microelectrode inserted into the cell, gastric myoelectrical activity can be recorded in two ways. Firstly, gastric electrical activity can be recorded with electrodes located in the immediate proximity of the muscle layers. This method is called gastroelectromyography. lt provides information about the electrical activity of larger groups of cells. Secondly, gastric myoelectrical activity can be recorded with the aid of electrodes at relatively large distances from the stomach (e.g. on the abdominal skin). This method is called electrogastrography. It provides rather global information about the electrical activity of the stomach. Whereas the method of electrogastrography is still in a relatively early experimental phase, the method of gastroelectromyography has frequently been used in studies on gastric myoelectric activity, both in health and disease. The published descriptions of the characteristics on normal gastroelectromyographic signals are not in complete accordance, however. No agreement exists about the existence and meaning of the so-called 1 Second potential 1 (Daniel, 1965, 1966) and about the relation between intracellular and extracellular electrical activity. Furthermore, gastroelectromyographic 1 iterature paid relatively 1 ittle attention to the rhythm of the so-cal led 1 Electrical Control Activity 1 (Sarna. 197

Assessment of oesophageal emptying in achalasia patients by intraluminal impedance monitoring

Oesophageal emptying can be assessed by radiographic and scintigraphic tests with radiation exposure or by multichannel intraluminal impedance monitoring (MII). The aim of this study was to evaluate the applicability of MII for the assessment of oesophageal emptying in achalasia patients. In 10 achalasia patients, impedance tracings were scored independently by three observers after ingestion of a 100-mL barium bolus. Bolus clearance time (BCT) and height of barium column were scored using fluoroscopic images acquired at 20-s intervals. All patients showed a low baseline impedance level in the distal oesophagus. Air trapping in the proximal oesophagus was detected in nine patients. BCT on MII was similar to that on fluoroscopy in 40-70% of the patients. Correlations between height of barium on fluoroscopy and fluid level on MII were poor to moderate at different time intervals. Concordance (Kendall's coefficient) between the three observers for assessment of fluid level on MII was 0.31 (P = 0.04) at 1 and 5 min, 0.26 (P = 0.08) at 10 and 0.44 (P = 0.01) at 15 min. We conclude that in achalasia patients, low baseline impedance levels and air entrapment in the proximal oesophagus limit the value of intraluminal impedance monitoring as a test of oesophageal emptying

Assessment of bolus transit with intraluminal impedance measurement in patients with esophageal motility disorders

BACKGROUND: The clinical management of patients with non-obstructive dysphagia is notoriously difficult. Esophageal impedance measurement can be used to measure esophageal bolus transit without the use of radiation exposure to patients. However, validation of measurement of bolus transit with impedance monitoring has only been performed in healthy subjects with normal motility and not in patients with dysphagia and esophageal motility disorders. The aim was, therefore, to investigate the relationship between transit of swallowed liquid boluses in healthy controls and in patients with dysphagia. METHODS: Twenty healthy volunteers and 20 patients with dysphagia underwent concurrent impedance measurement and videofluoroscopy. Each subject swallowed five liquid barium boluses. The ability of detecting complete or incomplete bolus transit by means of impedance measurement was assessed, using radiographic bolus transit as the gold standard. KEY RESULTS: Impedance monitoring recognized stasis and transit in 80.5% of the events correctly, with 83.9% of bolus transit being recognized and 77.2% of stasis being recognized correctly. In controls 79.8% of all swallows were scored correctly, whereas in patients 81.3% of all swallows were scored correctly. Depending on the contractility pattern, between 77.0% and 94.3% of the swallows were scored correctly. CONCLUSIONS & INFERENCES: Impedance measurement can be used to assess bolus clearance patterns in healthy subjects, but can also be used to reliably assess bolus transit in patients with dysphagia and motility disorders